This invention relates to a clutch assemblies for motor vehicles. Typical clutch assemblies have outer rings which are rotationally driven by the vehicle engine, inner rings in torque-transmitting linkage with the transmission input shaft of a speed-change gear, and at least one clutch plate or friction disc (lamella) provided on an outer ring and/or on an inner ring, which engages frictionally and withdraws under increasing slip.
Clutch assemblies are common in motor vehicles with manual transmissions. The clutch is operated by the driver through a clutch pedal when the vehicle is to accelerate from rest or when gears are to be shifted and changed.
Synchronized manual transmissions utilize synchronization mechanisms that adjust the gear speed to the engine speed when gears are being shifted and changed. These synchronization mechanisms fulfill their function only when the transmission input shaft is torque-free, which is why the clutch must be operated to shift gears in conventional systems.
Automatic transmissions torque converters have not met with universal acceptance for motor vehicles. They result in added manufacturing costs, loss of propulsion power, and added fuel consumption, which purchasers of small to medium-sized cars, in particular, are not always willing to accept.
Added fuel consumption, from an ecological point of view, also means increased exhaust emissions. Again, this is undesirable.
Driver's attitudes regarding automatic transmissions are also affected by psychological factors. Some drivers consider the manual shifting of gears sportive and like to be in direct control of their vehicle. Many drivers also attach importance to being able to tow their cars themselves, without lifting the vehicle's driving axle off the ground.
Semi-automatic transmissions are known for motor vehicles, which allow the driver of a vehicle to shift gears without operating the clutch. According to the current state of the art, however, these transmissions require extensive sensor and actuator technologies. The transmissions are accordingly complex, and at times sluggish in their shifting behavior.
A drivetrain design that is widely used in international vehicle manufacturing has a clutch assembly positioned between the engine and a manually operated synchronized speed-change gear on the transmission input shaft of the latter. It is the aim of the present invention to automate the function of such a clutch assembly so that it is required only as a startup clutch, but not needed for gear changes, while maintaining the benefits and attributes of the above design to the largest extent possible.